greeves Posted June 4, 2006 Report Share Posted June 4, 2006 Hi from Spain: I own this Pre-65 bike with a Villiers engine. Some days ago the piston blocked because it was overheated (a hot spanish day). When te engine cooled down a little it started again with no problems. Now sometimes the piston blocks for an instant. The piston looks ok, as well as the inside of the cylinder and the rings. Is there anibody that knows why and how can I stop this??? Thanks in advance. Quote Link to comment Share on other sites More sharing options...
bilco Posted June 4, 2006 Report Share Posted June 4, 2006 hi. sorry i dont know the answer to your problem,however i've just brought an old pre 65 but not sure what frame or even make of bike it is as most of it has been put together by diffrent bike's by the looks of it....what frame is your your's.your bike look's very nice.. thanks Quote Link to comment Share on other sites More sharing options...
greeves Posted June 4, 2006 Author Report Share Posted June 4, 2006 Hi bilco: The bike I think is made out of parts. The tank is a beamish, but a friend of myne is making me a new tank in UK replica to the old Francis Barnett Quote Link to comment Share on other sites More sharing options...
greeves Posted June 4, 2006 Author Report Share Posted June 4, 2006 To be honest I must say Rochepaule is not Scotland, only 20 pre-65 bikes there last year, and more than 300 twinshock.... Quote Link to comment Share on other sites More sharing options...
totalshell Posted June 4, 2006 Report Share Posted June 4, 2006 (edited) nice looking bike with a neat exhaust.. althoug it must be nice to ride in the sun all day and we are very jealous here on the pennine even though we are having a heat wave, i dont think the air temp will be the reason for the seizure I suspect that the bike may be running alittle lean and would richen it up a bit is it a 32a villiers with villiers carb if so i can dig out my jettings if the bike has prevously run ok is there any air getting in on the engine side of the carb.. Edited June 4, 2006 by totalshell Quote Link to comment Share on other sites More sharing options...
greeves Posted June 4, 2006 Author Report Share Posted June 4, 2006 Thank you for your interest Totalshell: The engine runned ok untill this happened. Then I open the cylinder to check inside. I have this photo from the carb and the filter. It is strange as everything inside the cylinder looks perfect. In fact the engine starts at the first kick and runs ok untill you need big power out of it, and it happens only sometimes. Somebody here in Spain told me this kind of cylinders need some polish inside, but I don Quote Link to comment Share on other sites More sharing options...
totalshell Posted June 4, 2006 Report Share Posted June 4, 2006 shouldnt need a polish in the bore none of my villiers 32a , 8e never had. your carb, inlet manifold and air filter are the same as on my old greeves i remeber that the needle length was critical at 47.5mm but will have to dig out my notes for the rest of the numbers, BUT as all engines differ they would only be a guide but more importantly if your engine ran well before then that is the best starting place. i would take the carb , air filter and manifold off and strip it all down and CLEAN EVERY PART including the filter and the cylinder/ manifold joints and put it all back together again before i changed anything.. then i would check the timing before i changed anything.. always remember the golden rule dont change ANYTHING unless you are absolutely certain it is broken.. Quote Link to comment Share on other sites More sharing options...
greeves Posted June 4, 2006 Author Report Share Posted June 4, 2006 I will try that this week as soon as I have some time, let you know then. Thanks Quote Link to comment Share on other sites More sharing options...
kevin j Posted June 6, 2006 Report Share Posted June 6, 2006 I have no knowledge of Villiers engine, but from similar bad experiences with 60's two strokes, I would look at these items: -plugged exhaust (had one that ran all day happy at 32 mph on the road, but would seize within half a minute at 35 mph. Found a restricted exhaust. At heavier loads, more air flow through exhaust, more back pressure, more residual cylinder gas, it overheated the piston and would seize. It would immediately restart and run again all day at 32 mph.) -piston tolerance, or ring end gap, expand under heat and load. Probably not the real cause as you say it ran well before, but could be aggravated by anything causing overheating. -air leaks, crank seals, carb boots, causing it to run lean and increase heat, which might cause the seizure. -timing changed? either retarded or advanced can cause higher exhaust temps -anything in carb restricting fuel flow, run lean, heat up. -fuel petcock or hose restriction, lean out at higher fuel demands. had a bmw that ran great all the time, but at higher speeds was lean due to petcock restriction, burned valves. kcj Quote Link to comment Share on other sites More sharing options...
unclebuck Posted June 6, 2006 Report Share Posted June 6, 2006 Re: the picture of the carb and filter. You do realise that the choke is closed in that position? That wouldn't help. Just wondering at it appears to be in the same position in the other pics as well. Quote Link to comment Share on other sites More sharing options...
mattylad Posted June 7, 2006 Report Share Posted June 7, 2006 What oil ratio are you running? Air cooled bikes need more oil that water cooled. I would use 40:1 instead of 50:1 and leaner. Quote Link to comment Share on other sites More sharing options...
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